Image processing methods often seek to emulate standard photographic reproduction in order to provide a wide range of familiar capabilities for users. One such example is noted in U.S. Pat. No. 4,941,057 to Lehmbeck et al., which shows an arrangement for making a proof sheet from a digital image, where each repetition of the image on the proof sheet shows the application of a different filter or screen. The photography analogy is helpful to many individuals who would make use of electronic image processing of images electrically acquired or generated.
One desirable photographic process is "dodging". In a dodging process, a photographic developer changes the local brightness of an area in an image during the printing stage by interposing a cut out, corresponding in size to the area for which brightness is to be changed, between the enlarger and the paper on which the image is to be printed. The cut out is attached to a wire (called the dodger or dodging stick) above the area of the image to be lightened during exposure. Because photographic paper is not exposed to the image (being blocked by the cutout) for the entire development time required to form uniform copy, that particular area has a different brightness level. A cut out moved slightly about the area of interest causes a blending or softening of the exposure at the edges. Of course, the cut out may either cover the local area, or cover the entire image except the local area. In electronic image composition, dodging would be a desirable effect to achieve.
U.S. Pat. No. 4,486,785 to Lasher et al. teaches a technique for enhancing a displayed image stored at a density of 1 data bit per pixel. Particularly, the Lasher patent shows method of reducing the visual impact of stepped edges of an image by selectively introducing gray scale pixels before the image is displayed. U.S. Pat. No. 3,984,828 to Beyers, Jr., teaches the use of alphanumeric characters for television channel number display which have borders of different color or brightness from the body of the characters. U.S. Pat. No. 3,781,849 to Baron et al., U.S. Pat. No. 3,868,673 to Mau, Jr. et al., U.S. Pat. No. 4,408,198 to Kudirka, all show video character generators which operate on edge information for the formation of the characters. U.S. Pat. No. 4,495,491 to Postl and U.S. Pat. No. 4,698,666 to Lake, Jr. et al., both show methods of highlighting a region on a display screen.
All the references cited herein are specifically incorporated by reference.